1. Cyhoeddwyd

   Species Radiation of Carabid Beetles (Broscini: Mecodema) in New Zealand

   Knapp, M., Goldberg, J. K., Emberson, R. M., Townsend, I. & Trewick, S. A., 23 Ion 2014, Yn: PLoS ONE. 9, 1

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

2. Cyhoeddwyd

   Mitogenomic evidence of close relationships between New Zealand's extinct giant raptors and small-sized Australian sister-taxa

   Knapp, M., Thomas, J. E., Haile, J., Prost, S., Ho, S. Y. W., Dussex, N., Cameron-Christie, S., Kardailsky, O., Barnett, R., Bunce, M., Gilbert, M. T. P. & Scofield, R. P., 1 Mai 2019, Yn: Molecular Phylogenetics and Evolution. 134, t. 122-128

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

3. Cyhoeddwyd

   Complete mitochondrial DNA genome sequences from the first New Zealanders

   Knapp, M., Horsburgh, K. A., Prost, S., Stanton, J. A., Buckley, H. R., Walter, R. K. & Matisoo-Smith, E. A., 6 Tach 2012, Yn: PNAS. 109, 45, t. 18350-18354

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

4. Cyhoeddwyd

   Using Local Agroecological Knowledge in Climate Change Adaptation: A Study of Tree-Based Options in Northern Morocco

   Kmoch, L., Pagella, T., Palm, M. & Sinclair, F., Hyd 2018, Yn: Sustainability. 10, 10, 17 t., 3719.

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

5. Cyhoeddwyd

   Preparation of titania mesoporous materials using a surfactant-mediated sol-gel method

   Kluson, P., Kacer, P., Cajthaml, T. & Kalaji, M., 1 Ion 2001, Yn: Journal of Materials Chemistry. 11, 2, t. 644-651

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

6. Cyhoeddwyd

   Titania thin films and supported nanostructured membranes prepared by the surfactant assisted sol-gel method

   Kluson, P., Kacer, P., Cajthaml, T. & Kalaji, M., 1 Medi 2003, Yn: Chemical and Biochemical Engineering Quarterly. 17, 3, t. 183-190

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

7. Cyhoeddwyd

   Are novel ecosystems the only novelty of rewilding?

   Klop-Toker, K., Clulow, S., Shuttleworth, C. & Hayward, M., 1 Tach 2020, Yn: Restoration Ecology. 28, t. 1318-1320

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

8. Cyhoeddwyd

   A transitional fossil mite (Astigmata: Levantoglyphidae fam. n.) from the early Cretaceous suggests gradual evolution of phoresy-related metamorphosis

   Klimov, P. B., Vorontsov, D. D., Azar, D., Sidorchuk, E. A., Braig, H. R., Khaustov, A. A. & Tolstikov, A. V., 23 Gorff 2021, Yn: Scientific Reports. 11, 1, 15113.

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

9. Cyhoeddwyd

   Sparing forests in Central Africa: re-use old logging roads to avoid creating new ones

   Kleinschroth, F., Healey, J. R. & Gourlet-Fleury, S., 2 Chwef 2016, Yn: Frontiers in Ecology and the Environment. 14, 1, t. 9-10

   Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

10. Cyhoeddwyd

    Effects of logging on roadless space in intact forest landscapes of the Congo Basin

    Kleinschroth, F., Healey, J., Gourlet-Fleury, S., Mortier, F. & Stoica, R. S., Ebr 2017, Yn: Conservation Biology. 31, 2, t. 469-480

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

11. Cyhoeddwyd

    Impacts of logging roads on tropical forests

    Kleinschroth, F. & Healey, J., Medi 2017, Yn: Biotropica. 49, 5, t. 620-635

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

12. Cyhoeddwyd

    How persistent are the impacts of logging roads on Central African forest vegetation?

    Kleinschroth, F., Healey, J. R., Sist, P., Mortier, F. & Gourlet-Fleury, S., 1 Awst 2016, Yn: Journal of Applied Ecology. 53, 4, t. 1127-1137

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

13. Cyhoeddwyd

    Corrigendum

    Kleinschroth, F., Healey, J., Sist, P., Mortier, F. & Gourlet-Fleury, S., 17 Medi 2016, Yn: Journal of Applied Ecology. 53, 6, t. 1890 1 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

14. Cyhoeddwyd

    Logging roads in tropical forests: Synthesis of literature written in French and English highlights environmental impact reduction through improved engineering

    Kleinschroth, F., Gourlet-Fleury, S., Gond, V., Sist, P. & Healey, J. R., 6 Rhag 2016, Yn: Bois et forêts des tropiques. 328, 2, t. 13-26

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

15. Cyhoeddwyd

    Implementing agricultural phosphorus science and management to combat eutrophication

    Kleinman, P. J., Sharpley, A. N., Withers, P. J., Bergstrom, L., Johnson, L. T. & Doody, D. G., 15 Chwef 2015, Yn: AMBIO. 44, 2, t. 297-310

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

16. Cyhoeddwyd

    The mosaic genome structure of the Wolbachia wRi strain infecting Drosophila simulans.

    Klasson, L., Westberg, J., Sapountzis, P., Naslund, K., Lutnaes, Y., Darby, A. C., Veneti, Z., Chen, L., Braig, H. R., Garrett, R., Bourtzis, K. & Andersson, S. G., 7 Ebr 2009, Yn: Proceedings of the National Academy of Sciences of the USA. 106, 14, t. 5725-5730

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

17. Cyhoeddwyd

    Navigation by extrapolation of geomagnetic cues in a migratory songbird

    Kishkinev, D., Packmor, F., Thomas, Z., Hans, W., Mouritsen, H., Chernetsov, N. & Holland, R., 12 Ebr 2021, Yn: Current Biology. 31, 7, t. 1563-1569

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

18. Cyhoeddwyd

    Compass orientation

    Kishkinev, D., Vonk, J. (gol.) & Shackelford, T. (gol.), 8 Chwef 2019, Encyclopedia of Animal Cognition and Behavior. Springer Nature

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion Cynhadledd › Cofnod mewn Gwyddoniadur/Geiriadur

19. Cyhoeddwyd

    Experienced migratory songbirds do not display goal-ward orientation after release following a cross-continental displacement: an automated telemetry study

    Kishkinev, D., Heyers, D., Woodworth, B. K., Mitchell, G. W., Hobson, K. A. & Norris, D. R., 23 Tach 2016, Yn: Scientific Reports. 6, 37326 .

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

20. Cyhoeddwyd

    Sensory mechanisms of long-distance navigation in birds: a recent advance in the context of previous studies

    Kishkinev, D., Rhag 2015, Yn: Journal of Ornithology. 156, t. S145-S161

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

21. Cyhoeddwyd

    Anosmic migrating songbirds demonstrate a compensatory response following long-distance translocation: a radio-tracking study

    Kishkinev, D., Anashina, A., Ishchenko, I. & Holland, R. A., Ion 2020, Yn: Journal of Ornithology. 161, 1, t. 47-57

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

22. Cyhoeddwyd

    Genome sequences of the human body louse and its primary endosymbiont provide insights into the permanent parasitic lifestyle.

    Kirkness, E. F., Hass, B. J., Sun, W., Braig, H. R., Perotti, M. A., Clark, J. M., Lee, S. H., Robertson, H. M., Kennedy, R. C., Elhaik, E., Gerlach, D., Kriventseva, E. V., Elsik, C. G., Graur, D., Hill, C. A., Veenstra, J. A., Walenz, B., Tubio, J. M., Ribeiro, J. M., Rozas, J., Johnston, J. S., Reese, J. T., Popadic, A., Tojo, M., Raoult, D., Reed, D. L., Tomoyasu, Y., Krause, E., Mittapalli, O., Margam, V. M., Li, H. M., Meyer, J. M., Johnson, R. M., Romero-Severson, J., VanZee, J. P., Alvarez-Ponce, D., Vieira, F. G., Aguade, M., Guirao-Rico, S., Anzola, J. M., Yoon, K. S., Strycharz, J. P., Unger, M. F., Christley, S., Lobo, N. F., Seufferheld, M. J., Wang, N., Dasch, G. A., Struchiner, C. J., Madey, G., Hannick, L. I., Bidwell, S., Joardar, V., Caler, E., Shao, R., Barker, S. C., Cameron, S., Bruggner, R. V., Regier, A., Johnson, J., Viswanathan, L., Utterback, T. R., Sutton, G. G., Lawson, D., Waterhouse, R. M., Venter, J. C., Strausberg, R. L., Berenbaum, M. R., Collins, F. H., Zdobnov, E. M. & Pittendrigh, B. R., 6 Gorff 2010, Yn: Proceedings of the National Academy of Sciences of the USA. 107, 27, t. 12168-12173

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

23. Cyhoeddwyd

    Ancient and modern stickleback genomes reveal the demographic constraints on adaptation

    Kirch, M., Romundset, A., Gilbert, M. T. P., Jones, F. C. & Foote, A. D., 10 Mai 2021, Yn: Current Biology. 31, 9, t. 2027-2036

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

24. Cyhoeddwyd

    Challenges to implementing greenhouse gas mitigation measures in livestock agriculture: A conceptual framework for policymakers

    Kipling, R. P., Taft, H. E., Chadwick, D. R., Styles, D. & Moorby, J., Chwef 2019, Yn: Environmental Science and Policy. 92, t. 107-115

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

25. Cyhoeddwyd

    Implementation solutions for greenhouse gas mitigation measures in livestock agriculture: A framework for coherent strategy

    Kipling, R. P., Taft, H. E., Chadwick, D. R., Styles, D. & Moorby, J., Tach 2019, Yn: Environmental Science and Policy. 101, t. 232-244

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

26. Cyhoeddwyd

    Biologically inspired herding of animal groups by robots

    King, A. J., Portugal, S. J., Strombom, D., Mann, R. P., Carrillo, J. A., Kalise, D., Croon, G. D., Barnett, H., Scerri, P., Gross, R., Chadwick, D. & Papadopoulou, M., 1 Chwef 2023, Yn: Methods in Ecology and Evolution. 14, 2, t. 478-486 9 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

27. Cyhoeddwyd

    Identification of the remains of King Richard III

    King, T. E., Fortes, G. G., Balaresque, P., Thomas, M. G., Balding, D., Delser, P. M., Neumann, R., Parson, W., Knapp, M., Walsh, S., Tonasso, L., Holt, J., Kayser, M., Appleby, J., Forster, P., Ekserdjian, D., Hofreiter, M. & Schurer, K., 2 Rhag 2014, Yn: Nature Communications. 5

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

28. Cyhoeddwyd

    Exploiting a dual-fluorescence process in Fluorene-Dibenzothiophene-S, S-dioxide co-polymers to give efficient single polymer LEDs with with broadened emission.

    King, S. M., Perepichka, I. I., Perepichka, I. F., Dias, F. B., Bryce, M. R. & Monkman, A. P., 24 Chwef 2009, Yn: Advanced Functional Materials. 19, 4, t. 586-591

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

29. Cyhoeddwyd

    Composition of biofilm communities in acidic mine waters as revealed by combined cultivation and biomolecular approaches.

    Kimura, S., Coupland, K., Hallberg, K. B., Johnson, D. B., Tsezos, M. (gol.), Hatzikioseyian, A. (gol.) & Remoudaki, E. (gol.), 1 Ion 2004, t. 1057-1065.

    Allbwn ymchwil: Cyfraniad at gynhadledd › Papur

30. Cyhoeddwyd

    Biodiversity of microbial populations in macroscopic “acid streamer” growths at an abandoned pyrite mine, elucidated using a combined cultivation-based and cultivation-independent approaches.

    Kimura, S., Hallberg, K. B., Johnson, D. B., Harrison, S. T. (gol.), Rawlings, D. E. (gol.) & Petersen, J. (gol.), 1 Ion 2005, t. 687-696.

    Allbwn ymchwil: Cyfraniad at gynhadledd › Papur

31. Cyhoeddwyd

    Biodiversity and geochemistry of an extremely acidic, low-temperature subterranean environment sustained by chemolithotrophy.

    Kimura, S., Bryan, C. G., Hallberg, K. B. & Johnson, D. B., 1 Awst 2011, Yn: Environmental Microbiology. 13, 8, t. 2092-2104

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

32. Cyhoeddwyd

    Sulfidogenesis in low pH (3.8-4.2) media by a mixed population of acidophilic bacteria

    Kimura, S., Hallberg, K. B. & Johnson, B., 1 Maw 2006, Yn: Biodegradation. 17, 2, t. 159-167

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

33. Cyhoeddwyd

    Highly contiguous assemblies of 101 drosophilid genomes

    Kim, B. Y., Wang, J., Miller, D. E., Barmina, O., Delaney, E. K., Thompson, A., Comeault, A., Peede, D., D'Agostino, E. R., Pelaez, J., Aguilar, J. M., Haji, D., Matsunaga, T., Armstrong, E., Zych, M., Ogawa, Y., Stamenković-Radak, M., Jelić, M., Savić Veselinović, M., Tanasković, M., Erić, P., Gao, J-J., Katoh, T. K., Toda, M. J., Watabe, H., Watada, M., Davis, J. S., Moyle, L., Manoli, G., Bertolini, E., Koštál, V., Hawley, R. S., Takahashi, A., Jones, C. D., Price, D. K., Whiteman, N. K., Kopp, A., Matute, D. R. & Petrov, D. A., 19 Gorff 2021, Yn: Elife. 10, e66405.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

34. Cyhoeddwyd

    Water table fluctuation in peatlands facilitates fungal proliferation, impedes Sphagnum growth and accelerates decomposition

    Kim, J., Rochefort, L., Hugron, S., Alqulaiti, Z., Dunn, C., Pouliot, R., Jones, T., Freeman, C. & Kang, H., 22 Ebr 2021, Yn: Frontiers Earth Science. 8, 579329.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

35. Cyhoeddwyd

    Elevated CO2 and high salinity enhance the abundance of sulfate reducers in a salt marsh ecosystem

    Kim, S-Y., Freeman, C., Lukac, M., Lee, S-H., Kim, S. D. & Kang, H., Maw 2020, Yn: Applied Soil Ecology. 147, 103386.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

36. Cyhoeddwyd

    Changing thermal sensitivity of bacterial communities and soil enzymes in a bog peat in spring, summer and autumn

    Kim, S-Y., Zhou, X., Freeman, C. & Kang, H., 1 Mai 2022, Yn: Applied Soil Ecology. 173, 104382.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

37. Cyhoeddwyd

    Functional and structural responses of bacterial and methanogen communities to 3-year warming incubation in different depths of peat mire

    Kim, S. Y., Freeman, C., Fenner, N. & Kang, H., 1 Meh 2012, Yn: Applied Soil Ecology. 57, t. 23-30

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

38. Cyhoeddwyd

    Characterization of a chitinolytic enzyme from Serratia sp KCK isolated from kimchi juice.

    Kim, H. S., Timmis, K. N. & Golyshin, P. N., 1 Gorff 2007, Yn: Applied Microbiology and Biotechnology. 75, 6, t. 1275-1283

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

39. Cyhoeddwyd

    Comparative analysis of soil microbial communities and their responses to the short-term drought in bog, fen, and riparian wetlands

    Kim, S. Y., Lee, S. H., Freeman, C., Fenner, N. & Kang, H., 1 Tach 2008, Yn: Soil Biology and Biochemistry. 40, 11, t. 2874-2880

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

40. Cyhoeddwyd

    Application of nanoscale secondary ion mass spectrometry to plant cell research

    Kilburn, M. R., Clode, P. L., Cliff, J. B., Stockdale, E. A., Herrmann, A. M., Murphy, D. V. & Jones, D. L., 1 Meh 2010, Yn: Plant Signaling and Behavior. 5, 6, t. 760-2 3 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

41. Cyhoeddwyd

    Structural insights into hydrolytic defluorination of difluoroacetate by microbial fluoroacetate dehalogenases

    Khusnutdinova, A. N., Batyrova, K., Brown, G., Fedorchuck, T., Chai, Y. S., Skarina, T., Flick, R., Petit, A-P., Savchenko, A., Stogios, P. & Yakunin, A., Hyd 2023, Yn: Febs Journal. 290, 20, t. 4966-4983 18 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

42. Cyhoeddwyd

    Prenylated FMN: biosynthesis, purification, and Fdc1 activation

    Khusnutdinova, A. N., Xiao, J., Wang, P-H., Batyrova, K., Flick, R., Edwards, E. & Yakunin, A., 2019, New Approaches for Flavin Catalysis. Palfey, B. A. (gol.). Elsevier, Cyfrol 620. t. 469-488 (Methods in Enzymology).

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion Cynhadledd › Pennod › adolygiad gan gymheiriaid

43. Cyhoeddwyd

    Reaction of microorganisms to the digestive fluid of earthworms.

    Khomyakov, N. V., Kharin, S. A., Nechitailo, T. Y., Golyshin, P. N., Kurakov, A. V., Byzov, B. A. & Zvyagintsev, D. G., 1 Ion 2007, Yn: Microbiology. 76, 1, t. 45-54

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

44. Cyhoeddwyd

    Elevated atmospheric CO2 changes phosphorus fractions in soils under a short rotation poplar plantation (EuroFACE).

    Khna, F., Lukac, M., Turner, G. & Godbold, D. L., 1 Gorff 2008, Yn: Soil Biology and Biochemistry. 40, 7, t. 1716-1723

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

45. Cyhoeddwyd

    Rabi cropping and promoting winter legumes in rice fallows in Nepal.

    Khanal, N., Joshi, K. D., Harris, D., Pande, S. (gol.), Stevenson, P. C. (gol.), Neupane, R. K. (gol.) & Grzywacz, D. (gol.), 17 Tach 2004.

    Allbwn ymchwil: Cyfraniad at gynhadledd › Papur

46. Cyhoeddwyd

    Mapping morpho-physiological characters on wheat chromosomes using QTL approach under salt stress

    Khan, A. S., Shahzad, A., Amin, A. Y., Steele, K. A., Hollington, P. A., Wyn Jones, R. G., Gorham, J. & Quarrie, S. A., 1 Rhag 2006.

    Allbwn ymchwil: Cyfraniad at gynhadledd › Papur

47. Cyhoeddwyd

    DNA markers for screening of wheat (Triticum aestivum L.) for salt tolerance

    Khan, A. S., Shahzad, A., Amin, A. Y., Steele, K. A., Hollington, P. A., Akhtar, J., Quresih, R. H. & Quarrie, S. A., 1 Rhag 2006.

    Allbwn ymchwil: Cyfraniad at gynhadledd › Papur

48. Cyhoeddwyd

    Grassland plants affect dissolved organic carbon and nitrogen dynamics in soil.

    Khalid, M., Soleman, N. & Jones, D. L., 1 Ion 2007, Yn: Soil Biology and Biochemistry. 39, 1, t. 378-381

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

49. Cyhoeddwyd

    Organic acid mediated nutrient extraction efficiency in three calcareous soils.

    Khademi, Z., Jones, D. L., Malakouti, M. J., Asadi, F. & Ardebili, M., 31 Maw 2009, Yn: Australian Journal of Soil Research. 47, 2, t. 213-220

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid

50. Cyhoeddwyd

    Multimodal correlative imaging and modelling of phosphorus uptake from soil by hyphae of mycorrhizal fungi

    Keyes, S., van Veelen, A., Fletcher, D. M., Scotson, C., Koebernick, N., Petroselli, C., Williams, K., Ruiz, S., Cooper, L., Mayon, R., Duncan, S., Dumont, M., Jakobsen, I., Oldroyd, G., Tkacz, A., Poole, P., Mosselmans, F., Borca, C., Huthwelker, T., Jones, D. L. & Roose, T., 1 Ebr 2022, Yn: New Phytologist. 234, 2, t. 688-703 16 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid